Smew Mergellus albellus 白秋沙鴨
Category I. Rare winter visitor.
IDENTIFICATION
Nov. 2018, James Kwok. First-year.
35-44 cm. Female or immature is largely grey with dark rufous crown and hind neck contrasting with white throat. First-year lacks black on the lores. Adult male eclipse as female but whiter on wing and darker above.
Jan. 2018, Michelle and Peter Wong.
Adult female has blackish lores. Adult male breeding very distinctive due to white head and body with black markings, including an obvious mask. In flight white along sides of mantle contrasts with dark grey centre of mantle and wings.
VOCALISATIONS
Usually, silent. Not reported to vocalise in HK.
DISTRIBUTION & HABITAT PREFERENCE
Apart from singles at Pui O, Lantau on 28 February 2011 and Tui Min Hoi (Sai Kung) on 8 November 2020, all have occurred in the Deep Bay area at Mai Po NR or in nearby fish pond areas such as Fung Lok Wai and San Tin.
OCCURRENCE
Now recorded annually in winter mainly from third week of December to the final week of February (Figure 1), with extreme dates of 10 November to 16 April.
Since the first record in December 1993 (Carey 1994), Smew has occurred increasingly regularly, and is now a scarce to rare winter visitor that has occurred annually since 2014; this increase is likely due to increased observer activity. Most birds are found before the end of the year, and long stays are typical, with the longest being the first record, which remained from 16 December 1993 to 16 April 1994.
BEHAVIOUR, FORAGING & DIET
A number of birds have remained for a few weeks, and at least two have moved to different sites in the Deep Bay area during their stay.
RANGE & SYSTEMATICS
Monotypic. Breeds between approximately 55oN and 70oN from Scandinavia east to the western coast of the Sea of Okhotsk, Kamchatka and Chukotka, and winters in scattered locations across northern and eastern Europe through the Black and Caspian Sea areas to Kazakhstan, Pakistan and east Asia as far north as Hokkaido (Carboneras and Kirwan 2020). In China it breeds in the far northeast of the country and is a winter visitor to north Xinjiang and the northeast as far south as the Chang Jiang (Yangtze River) floodplain (Liu and Chen 2020).
CONSERVATION STATUS
IUCN: Least Concern. Population trend decreasing.
Figure 1.
Carboneras, C. and G. M. Kirwan (2020). Smew (Mergellus albellus), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.smew.01
Carey, G. J. (1994). Smew at Mai Po: the first record for Hong Kong. Hong Kong Bird Report 1993: 115-116.
Liu, Y. and Y. H. Chen (eds) (2020). The CNG Field Guide to the Birds of China (in Chinese). Hunan Science and Technology Publication House, Changsha.
